A Numerical Research on the Heat Transfer Process for a General Passive Heat Removal System

A code module for simulating a general passive heat removal system composed of an elevated water tank, a heat exchanger and pipes connecting them is developed in this paper. Then, a typical heat transfer process in this heat removal system is calculated. According to the simulation results, the flash shows the most important impact of the heat transfer process for this passive heat removal system, especially the moment of the flash appearing. In order to design a scaled-down facility with the help of a scaling method to carry out experimental studies on the heat transfer process occurring in a PHRS for developing a more efficient heat removal system, all influence factors of flash should be conducted before a scaling analysis to make a good understanding for the flash. Finally, we get some qualitative conclusions based on sensitivity analyses for some influence parameters: 1) water temperature in the water tank, system flow resistance and the length of the outlet pipe should be ensured by designing according to scaling criteria strictly; 2) choosing a heat exchanger with geometric and material similarity can realize a consistency of heat transfer efficiency and 3) the liquid level in the water tank is less important.